Effecting relative displacement between pusher member and separator cage of a push-type centrifucal machine



Jan. 21, 1958 E. RUEGG 2,320,436

EFFEC NG RELATIVE DISPLACEMENT BE EN HE ER AND ARATOR CAGE OF A PUSH-TYPE TRI AL NE Filed Jan. 5, 1956 2 Sheets-Sheet 1 INVENTOR. Ernsl: Bile g'g Adcornegs United States Patent "EFFECTKNG RELATl'ViE" DISPLACEMENT BE- TWEEN .PUSHER MEMBER "AND SEPARA- TOR CAGE OF A PUSH-TYPE CENTRIFU- CAL 'MACHINE Ernst Ruegg,Kusnacht,-Switzerland,-.assignor to Escher Wyss Alstiengesellschaft,Zurich, Switzerland, :1 corporation of Switzerland -Application January 3, 1956, Serial No."557,189

Claims priority, application Switzerlandllanuary 13,1955

3 Claims. (Cl. 121-'-123) 'This invention relates to fluid-pressure motor. means, commonly hydraulic, for producing relative axial motion between two coaxial shafts, one encircling the other, the two shafts rotating together.

The claimed construction has the advantage that the controlling valve mechanism is in the main piston, so that fluid lines can be short, and packedjoints cant be reduced in number. This minimizes disturbing inertial effects and reduces the risks of leakage.

The distributing valve is mounted inthe main piston of the motor and shifts along a diametric line in such a way that centrifugal force, developed by rotation of the shafts, assists in completing the valve shift and tends to hold the valve in its shifted position, so that valves which control its motion may be of the utmost simplicity.

' The invention was developed for use in centrifuges of the pusher feed type, and will be described as so embodied.

'Two constructions in accordance with the-invention are illustrated in simplified form and by Way of example in the drawings, in which:

Fig. 1 is an axial section onthe line'II o-f Fig. 2 through apparatus for producing a relative axial displac ement between the pusher member and" separator cage of a push-type centrifugal machine.

Fig. 2 is a section on the lineIL-ll-bf'Fig. 1.

' Fig. 3 is a modification of the construction of the control apparatus, taken on the same section asin Fig. 2.

Fig. 4 is an axial longitudinal section onthe line 'IV-IV of Fig. 1.

' Fig. 5 is an axial longitudinal section through a pushto Fig. l.

The push-type centrifugal machine comprises a'hollow rotary shaft 1. A piston 2 serves to actuate that part of the centrifugal machine which is to be displaced. It is fixed by screws 3 to one end of a central shaft 4 which extends axially through the central bore of the hollow shaft 1 and by which is produced the connection with the part to be displaced. The two shafts are axially shiftable in relation to one another. Fixed to the end of the hollow shaft 1' coaxially therewith is a'cylinder 5 which revolves with the separator cage and 'which'is closed at its outer end by a cover 6. The piston 2 is-arranged in the cylinder Sso as to be axially displaceable in relation thereto and also revolves with the cylinder. It divides the cylinder space axially into. two. chambers 7 and 8.

The hollow shaft 1 is supported in a bearing 9 atthe end adjacent the cylinder 5. This bearing serves at thesame time for the supply of pressure fluid, which isv introduced through a pipe 10 and a connecting bore 11 into an annular duct 12 of the bearing.

The piston 2 is actuated by fluid, the-said piston int-- parting a reciprocatory movement to the moving part of the centrifugal machine. 'A control device, which consists of a-control valve.13 and-two. initialcontrohmembers 2,829,436 Patented Jan. 21, 1958 .l4.-.and .15, controls 1 thesadmission of; pressurefluid alternately toathe. two .sides; of the piston. Thisxcontrol deviceais arranged in-rthe -piston 2 itself. The control valvez13 is arranged in-the piston 2 in a bore 16. extend- .ingatransversely of the axis of rotation. It comprises twowcontrol pistons .17.- and. 18 and :also two valve-motor pistonaheads l9v and:20, :-and. 'it, isndisplaceable between twoend positions. which :aresymmetrical With-respect to the-rotational. axis ofsthegpiston 2 andvwhich are determined by two abutments consisting of annular washers 21 .anda22. The control piston. 17 controls theadmission =ofrpressurefluidv to the cylinder chamberssand the con- .trolpiston 18 controlssthe.admissionof pressure fluid to the. cylinder chamber 7.

alnEigs; l and .2, the control-valve 13 is shown in, its top. end, position. From the-annular: passage 12 of the bearing-9, the pressure fluid supplied by the-pipe 10 passes through transverse. bores 23min the hollow shaft 1 -into anannular passage-24 formed from inside in this hollow shaft. -Axtransverse bore 25 and an axially-extending longitudinal bore-.26 in the. central shaft-4 also produce aconnection.betweenttheannular. passage 24 and an annularr space'27aprovided in .the :piston 2 in the region-of the axis-so asto surround the control valve 13.

in :the position of the. control valve 13 as illustrated, the; path oftthecontrol fluid from theuannular space 27 into an annular space 28 disposed above it is open, the space"28 communicating through a passage 29 with; the workingspace-t; in the cylinder 5. :This causes piston 2 to move-toward head 6.. The'fluid, displaced fromtheworking space 7,:-passes:through a passagefill successivelyintrtwo annular spaces 31 'andGZ-surrounding' thecontrol valve 13--.and,-from thence. through apassage133. in: thepiston 2 .and an'opening- 34. of the cylinder-5 ,into a passage;35 extending axially :in .the cylinder. The passage 33'.-is shown in Fig. 2. and extends transversely of the axis .0f the control valve. From. the passage 35, the. fluid discharges into-a space-36 in-order to be returned from this space through a pipe 37 into a liquid container.

\On the other hand, if the control valve 13 is inits'bob tomend; position, the control pistonsf17 andslS are displaced .to such an extent vin the direction towardthezend washer.22 that a. connection isiproduced between the :annularspace 27 and the;annular: space 31, while. the connectionrbetween the spaces 31.3.I1d'323i816l086d. Inthis case, the. pressure 1 fluid passes, from the longitudinal bore 26 of the. centralshaft:4 through the annularspaces 27 and31' and-the passage 30 intofthe working space 7. The connection between the: annular. spaces 27 and28, on the other hand, is. closed by the 'piston' 17, while 'fluid cannow pass over from;the working space 8," through the bore.29. and. the; annularyspace 28, into an annular space '38 :disposed symmetricallyioffthe. annular space 32. A- bore 39 in: the piston 2 :andextending transversely ofthe axis ofzthe control valve 13. then permits the'discharge of fluid throughflan opening'40 of the'cylinder: 5 and. a longitudinal ;duct 41' extending inxthe latter in a symmetrical. positioniin relation to the passage-35,: the said duct 41 in turn openingintoj the space 36. I

flIn the one end position of. the control'valve' 13;.pressure fluid is. thus supplied to lthe'working space 8, and'iin the other. end position ofv the control valve, .to the working space 7. :Inthe one end position, therefore, the. control valve-13, frees the pathxto oneside of the piston:2 for the pressure liquid fromfthe longitudinal bore 26 of the central shaft 4 which .produces the connectionzbe tween the piston 2 and the partto be displaced and which travels in the central bore of the machine shaft 1, while invthe other, end-position; it-freesthe; pathto the other side .ofthe piston 2 for the; supplyaof=pressure.fluid;;'fromi this longitudinal, bore 26.

.;The,.piston.2iis thus; displaced axiallygini one direc'tifllt or the other. The arrangement of the control valve 13 in the piston itself has the advantage that it is only necessary to have a single pipe for the supply of pressure fluid to the rotating parts. Consequently, it is only necessary for the annular passage 12 to be sealed off against high pressure at the transition points from the fixed part to the rotating part. The reversal of the flow of fluid is effected only in short connecting ducts in the piston itself, while the same direction of flow obtains in the supply line as far as the annular duct 27 of the piston 2 and also the discharge ducts 33, 35 and 39, 41 respectively, always have the liquid flowing therethrough in the same direction.

In order constantly to produce a reciprocatory movement of the piston 2 in the cylinder 5, the control valve 13 is always to be changed over to its opposite end position upon the end position of the piston being reached. In the construction according to Figs. 1 and 2, this changeover is effected automatically by the initial control members 14 and 15. The member 14 controls the supply of pressure fluid from the annular passage 27 through the bores 42 and 43 to one end of the transversely extending bore 16 of the piston 2, i. e. to a space 44, which is defined on one side by the valve-motor piston head 20 of the control valve 13. On the other head, the initial control member controls the flow of pressure fluid through bores 45 and 46 to the other end of the transversely extending bore 16, i. e. to a space 47 which is defined on one side by the valve-motor piston head 19 of the control valve. The initial control members 14 and 15 are arranged in the piston 2 symmetrically of its axis of rotation and parallel thereto, and are fitted for longitudinal displacement in axial bores 48 and 49, respectively. They are formed with recesses 50 and 51, respectively, which are ofiset relatively to one another. The two control members 14 and 15 could, of course, also be replaced by a single control member for the control of the pressure fluid supply to both the spaces 44 and 47.

At the end position of the piston 2, as shown in Figures 1 and 4, the initial control members 14 and 15 are brought by abutment on the cylinder base into the position shown in Figure 4. The recess 50 of the member 14 is then at the place where the bores 42 and 43 meet. The pressure fluid can therefore pass from the annular space 27 through the ducts 42 and 43 into the space 44, the control valve 13 being urged against the end washer 21 and therefore held in the position shown. From the space 47, on the other hand, the fluid can flow out into the space 36 through an opening 52 and a duct extending longitudinally of the cylinder. Pressure fluid is supplied to the working space 8 and the piston 2 is moved toward the cylinder cover 6. The control valve 13 remains in the position shown until as the piston approaches the cylinder cover 6, the initial control members 14 and 15 strike against the cover 6 and are thus displaced toward the bearing end relatively to the piston 2. As a result, the recess 50 of the iniital control member 14 is displaced away from that position in which the bores 42 and 43 meet, so that the throughflow of pressure fluid is shut off. On the other hand, the recess 51 of the initial control member 15 is displaced to the position where the bores 45 and 46 meet. Thus, the path of flow of pressure fluid from the annular space 27 into the space 47 is opened, the control valve 13 being urged against the end washer 22. In the end position of the piston 2 at the cover end, a connection has been produced between the space 44 and the discharge space 36 through an opening 54 and a passage extending longitudinally of the cylinder 5, so that the fluid displaced with the movement of the control valve 13 toward the washer 22 is able to escape.

The initial control members 14 and 15 thus control the flow to the ends of the transversely extending bore 16 of the piston 2, i. e. to the spaces 44 and 47, respectively, adjoining the end.faces of the control valve 13 and in each case, when the piston 2 approaches one of its end positions and owing to abutment on the axial limits of the working space 7 or 8, they are shifted into a position in which, due to the opening of the path for pressure fluid to the corresponding end face of the control valve, the latter is changed over to its opposite end position and thereby initiates a reversal of movement of the piston 2.

This initial control device ensures that in all cases the control valve 13 is adjusted into the suitable end position when the piston 2 has to reverse its direction of travel. A changeover operation may, however, be obtained by more simple means, -as represented in Figure 3. With this arrangement, the provision of separate initial control members is dispensed with. Provided as supply duct for the fluid under pressure, a bore 56 extends radially outwardly from the space 27 in a direction at right angles to the axis of the control valve in the piston. Formed in the cylinder 5 is a groove 57 which, in the end position of the piston 2 as shown in Figure 1, produces a connection between the bore 56 and the space 44 below the control valve. Axially of the piston, the groove 57 is of such limited space that the said connection is produced solely in and in the vicinity of the end position. Provision must then be made for the fact that such an amount of pressure fluid can flow through the bore 56 that the control valve is adjusted from the lower to the upper end position before the piston 2 has again left its end position to such an extent that the connection has been broken.

In the end position of the piston 2 near the cylinder cover, with this method of reversal, a second groove extending symmetrically of the groove 57 in relation to the axis of the piston is to be arranged in the cylinder, which second groove has to produce the connection of the space 47 with the annular space 27 through a radial bore extending in the piston opposite to the bore 56.

With this arrangement, therefore, by means of grooves arranged in the cylinder, a connection between a pressure fluid supply duct and the space adjoining the corresponding end face of the control valve is always produced in the end positions of the piston 2, a reversal of the control valve into its opposite end position being effected by the fluid pressure from the said space, thereby initiating a reversal of the movement of the piston 2.

Figure 5 shows the assembly of the arrangement with a threestage push-type centrifugal machine. The hollow shaft 1 is arranged in a housing 58, which also encloses the cylinder 5 and is supported in a bearing 59 as well as in the bearing 9. Arranged in a housing 60 adjoining the housing 58 are three separator cages 61, 62 and 63 successively supplied with the material being centrifuged. The cage 61 is mounted by a boss 64 on that end of the central shaft 4 which projects from the shaft 1. The cage 63 is connected fast to the cage 61 by means of struts or bars 65. The cage 62, on the other hand, is rigidly connected by means of a boss 66 to that end of the shaft 1 which projects beyond the bearing 59. Bars 67 extending through the boss 64 also produce a rigid connection between the boss 66 and a pusher member 68 arranged in the cage 61.

The material to be centrifuged is introduced through a pipe 69 and conveyed on to the cage 61 by means of a funnel 70 rigidly connected to the pusher member 68. With the axial reciprocatory movement of the central shaft 4, the cages 61 and 63 are concurrently moved. The cage 61 and the fixed pusher member 68 which cooperates with the cage 61, are moved relatively to one another, and this movement displaces the material on the cage 61 toward the end of the latter, where it passes on to the cage 62, which is fixed axially. For the layers of material forming on this cage, the end of the cage 61 serves as a pusher member and the reciprocatory movement thereof causes the material to travel forward on to the last cage 63. Due to the axial reciprocatory movement thereof with the cage 61, the end of the axially fixed cage- 62 again serves as pusher member, whereby the material is finally expelled from the cage 63 and is collected in a part 71 of the housing 60 serving as collecting device, in order then to drop downwardly through an opening 72.

The housing 58 also has arranged therein a motor 73 which serves for the drive of the centrifugal machine. The cylinder 5 is at the same time designed as a belt pulley formed with grooves 74, the machine being driven by V-belts which extend around the cylinder 5 and a driving pulley 76 arranged on the motor shaft. The part of the cylinder 5 which is not used for the belt drive may also be used in known manner as a brake drum.

Due to the fact that the control device 13 is arranged in the piston 2 itself, the machine is given a very compact construction. No control devices arranged externally of the machine are to be provided, which devices can render access to the machine difficult while it is running. With the constructional form described, the control piston can readily be removed with the control means after removing the cover 6, this being effected rearwardly and axially, so that also an inspection can easily be made.

What is claimed is:

1. The combination of two coaxial shafts, one encircled by the other and movable axially relatively thereto while rotating therewith; bearings in which the outer shaft is rotatable; an expansible chamber motor comprising a main cylinder closed at its ends and mounted coaxially on the encircling shaft and a double-acting main piston reciprocable in said main cylinder and connected with the encircled shaft to shift said shaft relatively to the encircling shaft; a combined distributing valve and valve-shifting piston means mounted in a combined ported valve seat and valve-motor cylinder extending diametrically within said main piston and substantially symmetrical with reference to the common axis of the shafts, there being a supply passage leading through the inner shaft to a supply port substantially at mid-length of said valve seat, there being exhaust ports leading from opposite end portions of the valve seat to and thence through coacting passages in the main piston and cylinder, and there being two motor ports intermediate said supply and exhaust ports and each leading through the main piston to a different working space in said main cylinder, said ports being controlled by said distributing valve to cause the main piston to shift reversely in response to reverse shifts of said distributing valve; and valve means rendered effective by arrival of the main piston at its opposite limits of motion to energize reversely said valve-shifting piston means.

2. The combination defined in claim 1 in which the valve means last named is effective to energize the valveshifting piston means past its mid-stroke and centrifugal force is elfective to complete the terminal portion of such stroke.

3. The combination defined in claim 2 in which said last-named valve means comprises ports in the main cylinder controlled by the main piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,254,644 Allen Jan. 29, 1918 1,284,225 Bogart Nov. 12, 1918 1,928,341 Ter Meer Sept. 26, 1933 1,944,391 Altpeter Jan. 23, 1934 2,685,370 Ruegg Aug. 3, 1954 2,699,152 Russell Jan. 11, 1955 2,789,544 Dermond Apr. 23, 1957 2,789,545 Dolza et a1 Apr. 23, 1957 

